Sewing machine with trimming mechanism

ABSTRACT

A sewing machine having a tirmming mechanism which is readily attachable to and readily removable from the sewing machine drive mechanism, without dismantling the sewing machine or disassembling its drive mechanism. The invention comprises the use of an elongated main drive shaft extending from the rotary drive mechanism of the sewing machine to and beyond the reciprocatory needle drive mechanism thereof, and the attachment of the trimming mechanism and the feed dog driving mechanism to said elongated main drive shaft.

United States Patent 11 1 Desperak et a1.

14 1 July17, 1973 i 1 SEWING MACHINE WITH TRIMMING MECHANISM [75] Inventors: Sam Desperak, Bayside; Joseph Roschko, Brooklyn; Max Katz,

Flushing, all of NY.

[73] Assignee: Advance Sewing Machine Co. Inc.,

New York,N.Y.

[22] Filed: Jan. 3, 1972 [21] Appl. No.: 214,731

52 U.S. Cl. 112/123 51 Int. (:1 D05b 37/02 581 Field of Search 112/123, 122, 129, 112/126, 127

[56] References Cited UNITED STATES PATENTS 1,136,846 4/1915 Thompson 112/123 2,645,193 7/1953 Chinnici 112/123 3,439,638 4/1969 Zuk 112/219 A 2,667,850 2/1954 Galkin 112/122 3,054,366 9/1962 Crcmcr ll2/l23 Primary Examiner-J1. Hampton Hunter Att0mey-Samue1 J. Stoll et a1.

[5 7 ABSTRACT A sewing machine having a tirrnming mechanism which is readily attachable to and readily removable from the sewing machine drive mechanism, without dismantling the sewing machine or disassembling its drive mechanism. The invention comprises the use of an elongated main drive shaft extending from the rotary drive mech anism of the sewing machine to and beyond the reciprocatory needle drive mechanism thereof, and the attachment of the trimming mechanism and the feed dog driving mechanism to said elongated main drive shaft.

5 Claims, 9 Drawing Figures PATENTEB JUU 1m sam anrs SEWING MACHINE WITH TRIMMING MECHANISM BACKGROUND OF THE INVENTION 1. Field of the Invention Sewing machines, mainly industrial sewing machines,

used in connection with work pieces which require trimming during the sewing operation.

2. Description of the Prior Art The closest prior art known to applicant consists of U.S. Pat. No. 2,645,193, issued to Michael Chinnici on July 14, 1953, and the U.S. Pat. references cited therein, namely:

No. 249,571 Baker Nov. 15, 1881 No. 790,560 Nike May 23, 1905 No. 1,111,339 Weis et al. Sept. 22, 1914 No. 1,353,534 Hughes Sept. 21, 1920 No. 2,011,513 Carmichael Aug. 13, 1935 No. 2,021,700 Pugach Nov. 19, 1935 The Chinnici patent shows the principle of a trim ming mechanism on a sewing machine, connected to and driven by the main drive shaft of said sewing machine. However, this patent also shows the problem which the present invention seeks to solve, namely, the problem of mechanically attaching the trimming mechanism to the main drive shaft of the sewing machine. Installation of the Chinnici trimming mechanism requires that the sewing machine by partially dismantled and the main drive mechanism be partially disassembled in order to mount an eccentric on the main drive shaft. The trimming mechanism is connected to said eccentric in order to produce a reciprocatory movement of the movable trimming blade when the sewing machine is in operation. Removal or replacement of the trimming mechanism requires the same partial dismantling and partial disassembling of the sewing machine and its main drive mechanism.

SUMMARY OF THE INVENTION The present invention is based on the principle of extending the length of the main drive shaft of the sewing machine so that it will project beyond the reciprocatory needle drive mechanism. It is to be the outwardly projecting end of the elongated drive shaft that the trimming mechanism is connected. The outwardly projecting end of the elongated drive shaftis fully accessible without dismantling any part of its drive mechanism. The trimming mechanism may therefore be readily installed and equally as readily removed, without taken apart any of the sewing machine mechanisms or assemblies. This feature of accessibility to the main drive shaft without disassembling any of the parts of the sewing machine is equally applicable to the feed dog drive mechanism. An eccentric is provided on the outwardly projecting end of the elongated drive shaft and a connecting linkage is provided between said eccentric and the feed dog.

The invention also provides an adaptor as the means for elongating a conventional drive shaft. The adaptor embodies two eccentrics, one to drive the trimming mechanism and the other to drive the feed dog.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an end view of a sewing machine showing how a trimming mechanism and a feed dog drive mechanism may be attached to the outwardly projecting end of an elevated main drive shaft.

FIG; 2 is a front view of said trimming mechanism and feed dog drive mechanism, including the outwardly projecting end of the main drive shaft of the sewing machine.

FIG. 3 is a top view of the trimming mechanism and feed dog drive mechanism and the elevated main drive shaft to which they are operatively connected.

FIG. 4 is a more detailed view of the main drive shaft, including sectional views of its bearings, said sectional view being taken on the line 4-4 of FIG. 3.

FIG. 5 is a fragmentary transverse section on the line 5-5of FIG. 3. 1

FIG. 6 is a fragmentary sectional view through the trimming mechanism.

FIG. 7 is a sectional view through said trimming mechanism taken on the line 77 of FIG. 6.

FIG. 8 is a view looking in the direction of arrows 8,8 of FIG. 3.

FIG. 9 is a view of a modification of the present invention showing an adapter method of extending the length of the main drive shaft of the sewing machine.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION Referring now to the first embodiment of the invention as illustrated in FIGS. 1 through 8 of the drawing, it will be seen that it includes a standard sewing machine head 10 mounted on a frame or base 12 and a main drive shaft 14 extending longitudinally of said head from its rotary drive mechanism (not shown) at the right of FIG. 2 to and beyond the reciprocatory needle drive mechanism 16. The rotary drive mechanism is connected by conventional means to said main drive shaft 14 and said reciprocatory needle drive mechanism 16 to drive both in synchronication with each other. The outwardly projecting end of the elevated drive shaft 14, that is, the left end as viewed in FIG. 2, has a disc 18 connected coaxially therewith. Formed across said disc, diametrically thereof, is a channel 20. This channel is adapted to receive a bar 22 which is integral with a second disc 24. Screws 26 secure disc 24 to disc 18 and thereby hold bar 22 in place in channel 20. A partially threaded pin 28 is affixed to bar 22 through disc 24, and this pin is offset a predetermined (or adjustable) distance from the axial center of the disc 18 and main drive shaft 14. Pin 28 is an eccentric drive pin, which, it will be seen, drives the feed dog 30 of the sewing machine.

Mounted on eccentric drive pin 28 is acrank 32, being held in place on said pin by means of a nut 34. The lower end 36 of crank 32 is bifurcated, as clearly appears in FIG. 2, and a cross-pin 38 extends across and is attached to said bifurcated end of crank 32. Pivotally mounted on cross-pin 38 is one end of a second crank 40, and its opposite end is connected to an extension 42a of stud shaft 42 on rocket 44. A coupling 42b joins extension 42a to stud shaft 42.

Below stud shaft 42 is shaft 46 on which rocker 44 rocks. Above stud shaft 42 on rocker 44 is another shaft 48. A crank arm 50 is connected at one end to said shaft 48 and at its opposite end to bracket 52 on feed dog 30.

When the sewing machine is in operation, the rotary drive mechanism (not shown) drives shaft 14 with its terminal disc 18 and causes them to rotate in synchronization with the operation of the reciprocal needle drive mechanism 16. This will cause eccentric drive pin 28 to move in a circular path concentric with the longitudinal axis of said drive shaft 14. The eccentric pin will thereby be caused to drive crank 40, rocker 44 and crank 50 and thereby operate the feed dog 30 in synchronization with the operation of reciprocal needle drive mechanism 16.

Main drive shaft 14 also drives trimming mechanism 60, and more particularly the pivotally mounted cutting blade 62 thereof. This pivotal blade cooperates with a stationary blade 64 to trim the material which is being sewn. More particularly, trimming mechanism 60 includes a bracket 66 which is secured to the base or frame 12 of the sewing machine. It will be observed in FIGS. 1 and 6 that a sewing machine frame member 68 is provided with a cross-bar 70 and bracket 66 is provided with a complementary groove 72, which slidably receives and engages said bar 70. Slots 74 are formed in bracket 66, and screws 76, extending through said slots, adjustably attach said bracket to frame element 68.

Extending through bracket 66 is a shaft 78, and mounted on said shaft is a bifurcated bellcrank 80. It is to one of the arms 82 of said bifurcated bellcrank 80 that the movable cutting blade 62 is attached. The stationary cutting blade 64 is attached to bracket 66. The movable cutting blade 62 is fixed relative to said bellcrank 80, and it is movable in relation to stationary blade 64 in the sense that the bell-crank 80 is itself pivotally movable in relation to bracket 66 and the stationary blade 64 which is secured thereto. Also, spring 77 on shaft 78, between bracket 66 and bellcrank 80, urges the bellcrank leftwardly, as viewed in FIG. 6, and thereby holds the two blades in tensioned cutting engagement with each other.

Bellcrank 80 includes a downwardly projecting arm 84. Secured thereto is a screw-threaded element 86 having a cylindrical unthreaded shank 88. It will be seen that a crank 90 interconnects cylindrical shank 88 with eccentric 92 on main drive shaft 14. More particularly, the first mentioned end of crank 90 is provided with a bearing 94 which is mounted on cylindrical shank 88, and its opposite end is provided with a second bearing 96 which is mounted on eccentric 92. When the sewing machine is in operation, main drive shaft 14 is caused to rotate about its longitudinal axis, and when this occurs eccentric 92 causes crank 90 to reciprocate leftwardly and rightwardly as viewed in FIG. 1 This in turn causes the bellcrank to oscillate about a longitudinal axis of shaft 78, and the result is a shearing action between cutting blades 62 and 64. It will also be understood that the cutting blades are adjustably and replaceably secured to their respective supports. Thus, stationary blade 64 is mounted in a blade holder 98, and said blade holder is secured by means of screw 100 to fixed bracket 66. A similar arrangement is provided for securing cutting blade 62 to arm 82 of bell-crank 80. The particular shape of the blades is purely functional. Cutting blade 62 is hookshaped in side view to enable it to hook loose threads and to bring them into shearing engagement between the two cutting blades. p9

It will be noted that fixed blade 64 is adjustably mounted relative to the movable blade 62. The adjustment is between bracket 66 and shaft 78 which supports the bracket. Clamping screws 101 secure the bracket to the shaft in adjusted position. See FIGS. 6 and 7. It will also be noted that a blade release is provided in the form of eccentric 102. When this eccentric is rotated, its high side engages post 103 on bellcrank and causes said bellcrank (and shaft 78) to move rightwardly, as viewed in FIG. 6, against the tension of spring 77. This provides clearance between the blades.

Wherever necessary, balancing elements are provided. Illustrative is balancing element 104, but it will be understood that such balancing means are provided wherever smooth operation of the machine requires. It should also be understood that the above described preferred form of the invention may be modified, particularly when applied to different types of sewing machines, within the broad scope of the appended claims. FIG. 9 shows an adapter which is used to extend the effective length of a conventional drive shaft 112 so that the present invention may be applied thereto. Adapter 110 comprises a short shaft 114, a coupling element 116 at one end of said shaft which engages and is secured to a complementary coupling element 118 on drive shaft 112, a mounting disc 120 at the opposite end of shaft 1 14 for an eccentric, and an eccentric cam element 122 on said shaft 114 between said coupling and mounting elements 118 and 120.

Mounting disc 120 corresponds to disc 18 with its diametrically extending channel 20 and mounting 120 is intended to perform the same function as disc 18, namely, to support bar 22 with its disc 24 and eccentric drive pin 28. The feed dog driving mechanism as above described is driven by pin 28, and it is immaterial whether said pin is mounted on disc 18 or disc 120.

Similarly, eccentric 122 corresponds to eccentric 92 above described and the trimming mechanism is driven by said eccentric 122 precisely as it is driven by eccentric 92.

It is evident from the foregoing that adapter 110 makes it possible to apply the present invention to a sewing machine having a conventional drive shaft 112, and precisely the same trimming and feed dog operating mechanisms which are shown in FIGS. 1-7 may be connected to and driven by adapter 110 and, more particularly, eccentric cam element 122 and drive pin 28.

The foregoing illustrates preferred forms of this invention and it will be understood that these forms may be modified and other forms may be provided within the broad scope of the appended claims.

We claim:

1. In a sewing machine having a head, a rotary drive mechanism at one end of the head a reciprocatory needle drive mechanism at the opposite end of the head, and a feed dog mounted for oscillatory movement below said needle drive mechanism, the improvement comprising:

a. an elongated main drive shaft connected at one end to the rotary drive mechanism and extending at its opposite end beyond the needle drive mechanism and the feed dog,

b. a pair of eccentrics connected to said opposite end of the main drive shaft,

c. a trimming mechanism mounted adjacent said feed (1. a first drive mechanism operatively connecting one of said eccentrics to said feed dog to cause it to engage in oscillatory movement synchronized with the operation of the needle drive mechanism, and

e. a second drive mechanism operatively connecting the second of said eccentrics to said trimming mechanism to cause it to operate in reciprocatory manner in synchronization with the oscillatory movement of the feed dog,

f. said elongated main drive shaft comprising a pair of interconnected parts,

g. one of said parts consisting of a drive shaft which extends to but not beyond the needle drive mechanism and feed dog,

h. the other of said parts consisting of an extension piece which is secured to said last mentioned drive shaft and which extends beyond said needle drive mechanism and feed dog,

i. both of said eccentrics being connected to said extension piece.

2. The combination of claim 1, wherein:

a. the trimming mechanism comprises a pair of cutting blades mounted in shearing relationship,

b. a fixed bracket supporting one of said cutting blades, and

c. a pivoted bellcrank supporting the other of said cutting blades,

said second drive mechanism comprising a crank which interconnects the second eccentric with the bellcrank.

3. The combination of claim 2, wherein:

a. the bellcrank is bifurcated to provide a pair of spaced horizontal arms,

b. said arms being both pivotally mounted on a common shaft to provide a wide bearing support for the bellcrank,

c. the second cutting blade being mounted on one of said bellcrank arms,

d. said bellcrank also having a downwardly projecting arm which is connected to the crank of the second drive mechanism interconnecting the bellcrank with the second eccentric.

4. The combination of claim 1, wherein the first drive mechanism comprises:

a. a crank connected to the first eccentric,

b. a second crank connected to the feed dog, and

c. connecting means between said cranks.

5. In a sewing machine having a head, a rotary drive mechanism at one end of the head, a reciprocatory needle drive mechanism at the opposite end of the head, and a feed dog mounted for oscillatory movement below said needle drive mechanism, the improvement comprising:

a. an elongated main drive shaft connected at one end to the rotary drive mechanism and extending at its opposite end beyond the needle drive mechanism and the feed dog,

b. a pair of eccentrics connected! to said opposite end of the main drive shaft, beyond the needle drive mechanism and the feed dog,

. a trimming mechanism mounted adjacent said feed dog, also beyond said needle drive mechanism,

. a first drive mechanism operatively connecting one of said eccentrics to said feed dog to cause it to engage in oscillatory movement synchronized with the operation of the needle drive mechanism, and

e. a second drive mechanism operatively connecting the second of said eccentrics to said trimming mechanism to cause it to operate in reciprocatory manner in synchronization with the oscillatory movement of the feed dog,

f. said first drive mechanism comprising a crank connected to the first eccentric,

g. a second crank connected to the feed dog, and

h. connecting means between said cranks,

i. said trimming mechanism comprising a pair of cutting blades mounted in shearing relationship,

j. a fixed bracket supporting one of said cutting blades, and

k. a pivoted bellcrank supporting the other of said cutting blades,

1. said second drive mechanism comprising a crank which interconnects the second eccentric with the bellcrank,

In. said bellcrank being bifurcated to provide a pair of spaced horizontal arms,

11. said arms being both pivotally mounted on a common shaft to provide a wide bearing support for the bellcrank,

o. the second cutting blade being mounted on one of said bellcrank arms,

p. said bellcrank also having a downwardly projecting arm which is connected to the crank of the second drive mechanism interconnecting the bellcrank with the second eccentric. 

1. In a sewing machine having a head, a rotary drive mechanism at one end of the head a reciprocatory needle drive mechanism at the opposite end of the head, and a feed dog mounted for oscillatory movement below said needle drive mechanism, the improvement comprising: a. an elongated main drive shaft connected at one end to the rotary drive mechanism and extending at its opposite end beyond the needle drive mechanism and the feed dog, b. a pair of eccentrics connected to said opposite end of the main drive shaft, c. a trimming mechanism mounted adjacent said feed dog, d. a first drive mechanism operatively connecting one of said eccentrics to said feed dog to cause it to engage in oscillatory movement synchronized with the operation of the needle drive mechanism, and e. a second drive mechanism operatively connecting the second of said eccentrics to said trimming mechanism to cause it to operate in reciprocatory manner in synchronization with the oscillatory movement of the feed dog, f. said elongated main drive shaft comprising a pair of interconnected parts, g. one of said parts consisting of a drive shaft which extends to but not beyond the needle drive mechanism and feed dog, h. the other of said parts consisting of an extension piece which is secured to said last mentioned drive shaft and which extends beyond said needle drive mechanism and feed dog, i. both of said eccentrics being connected to said extension piece.
 2. The combination of claim 1, wherein: a. the trimming mechanism comprises a pair of cutting blades mounted in shearing relationship, b. a fixed bracket supporting one of said cutting blades, and c. a pivoted bellcrank supporting the other of said cutting blades, said second drive mechanism comprising a crank which interconnects the second eccentric with the bellcrank.
 3. The combination of claim 2, wherein: a. the bellcrank is bifurcated to provide a pair of spaced horizontal arms, b. said arms being both pivotally mounted on a common shaft to provide a wide bearing support for the bellcrank, c. the second cutting blade being mounted on one of said bellcrank arms, d. said bellcrank also having a downwardly projecting arm which is connected to the crank of the second drive mechanism interconnecting the bellcrank with the second eccentric.
 4. The combination of claim 1, wherein the first drive mechanism comprises: a. a crank connected to the first eccentric, b. a second crank connected to the feed dog, and c. connecting means between said cranks.
 5. In a sewing machine having a head, a rotary drive mechanism at one end of the head, a reciprocatory needle drive mechanism at the opposite end of the head, and a feed dog mounted for oscillatory movement below said needle drive mechanism, the improvement comprising: a. an elongated main drive shaft connected at one end to the rotary drive mechanism and extending at its opposite end beyond the needle drive mechanism and the feed dog, b. a pair of eccentrics connected to said opposite end of the main drive shaft, beyond the needle drive mechanism and the feed dog, c. a trimming mechanism mounted adjacent said feed dog, also beyond said needle drive mechanism, d. a first drive mechanism operatively connecting one of said eccentrics to said feed dog to cause it to engage in oscillatory movement synchronized with the operation of the needle drive mechanism, and e. a second drive mechanism operatively connecting the second of said eccentrics to said trimming mechanism to cause it to operate in reciprocatory manner in synchronization with the oscillatory movement of the feed dog, f. said first drive mechanism comprising a crank connected to the first eccentric, g. a second crank connected to the feed dog, and h. connecting means between said cranks, i. said trimming mechanism comprising a pair of cutting blades mounted in shearing relationship, j. a fixed bracket supporting one of said cutting blades, and k. a pivoted bellcrank supporting the other of said cutting blades, l. said second drive mechanism comprising a crank which interconnects the second eccentric with the bellcrank, m. said bellcrank being bifurcated to provide a pair of spaced horizontal arms, n. said arms being both pivotally mounted on a common shaft to provide a wide bearing support for the bellcrank, o. the second cutting blade being mounted on one of said bellcrank arms, p. said bellcrank also having a downwardly projecting arm which is connected to the crank of the second drive mechanism interconnecting the bellcrank with the second eccentric. 